Direct current motor having improved commutation means

ABSTRACT

A direct current motor of the type having a bar magnet rotor utilizes magnetic reed switches as a commutation means. The reed switches are operable by the bar magnet rotor to effect commutation of the motor.

Q United States Patent 1 78,359

Peterson 1 July 18, 1972 [54] DIRECT CURRENT MOTOR HAVING 3,185,9105/1965 Knapp ..318/254 X IMPROVED COMMUTATION MEANS 3,546,507 12/1970Wengel ..310/46 X 3,297,891 l/l967 Foran, Jr. ..310/46 [72] Inventor:Donovan F. Peterson, 655 Meadow Lane, 3,435,313 3/1969 Siefert eta]...318/138 Elm Gr Wi 53122 3,096,467 7/1963 Angus et al ..3l8/l 38 [22]Filed: 1970 Primary Examiner-D. F. Duggan [21] AppL No: 100,061AltorneyAndrus, Sceales, Starke & Sawall [57] ABSTRACT [52] "'3 310/46 Adirect current motor of the type having a bar magnet rotor [51] Int. Cl..JIOZR 29/02 utilizes magnetic reed switches as a commutation means. Theof &arch 46, reed witches are operable the bar magnet rotor to effectcommutation of the motor.

"[56] References Cited UNITED STATES PATENTS 5 Claims, 6 Drawing Figures2,558,540 6/1951 Clos ..310/46 M M 2g V 4d 42 34 I 30 i m J /2 40 a 1 iJ0 fa L- P Fae/0R DIRECT CURRENT MOTOR HAVING IMPROVED COMNIUTA'IIONMEANS BACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention relates to electric motors, and more specifically to a directcurrent motor having an improved commutation means.

2. Description of the Prior Art Direct current motors produce torquethrough the interaction of current carrying conductors and a magneticfield. The current carrying conductors or the magnetic field must berelatively rotatable with respect to the other. In a typical directcurrent motor, a plurality of current carrying conductors areincorporated in a rotatable armature member and the magnetic field isproduced by stationary field windings and pole pieces. However, directcurrent motors may also be constructed with stationary current carryingconductors and a rotatable magnetic member, such as a permanent magnetrotor or a slipring energized electromagnet. The invention describedherein has presently been found more suitable for incorporation in thelatter type of direct current motor.

In either type of direct current motor, the motor requires a switchingmeans which sequentially supplies direct current energization to thecurrent carrying conductors as the rotary member of the motor revolves,thereby to maintain the essential torque producing relationships in themotor. Such a switching means is termed a commutator.

In the past, commutators have been constructed of a number of metal baror plate segments which are positioned on a drum and mounted coaxiallywith the rotating member of the motor. The segments of the commutatorare insulated from each other as by mica or other insulating material.Two or more brushes, typically carbon blocks or metal leaf springs, bearon the drum so as to provide the desired switching action as the drum isrotated.

While commutators incorporating such a construction have provenworkable, they suffer numerous shortcomings. Since there is movementbetween the commutator segments and brushes, there is inevitably wear onone or both of the commutator elements, resulting in oxidation, dirt,sparking, vibration, misalignment etc. in the commutator. Thesephenomena lessen the electrical and mechanical efficiency andreliability of the commutator in many ways and necessitate the eventualreplacement of the elements of the commutator.

SUMMARY OF THE PRESENT INVENTION It is, therefore, the object of thepresent invention to provide a direct current motor having an improvedcommutation means.

It is a further object of the present invention to provide such a motorin which the commutation means is capable of effecting the switchingoperation with essentially no wear and which therefore has extremelylong, if not unlimited, service life.

It is a more specific object of the present invention to pro vide animproved commutation means for a direct current motor in which thereappears a rotating magnetic field.

In a typical embodiment of the present invention, the motor includesstationary windings of conductors which are selectively switched by thecommutator so that the current carrying ones of the conductors aremaintained in the correct torque producing relationship with a rotatingbar magnet producing the rotating magnetic field.

The essence of the present invention lies in the use of magnetic reedswitches, or the like, to effect the switching action of the commutatorresponsive to the magnetic field of the rotating bar magnet. Theswitches are interposed between the conductor windings and a source ofdirect current such as a battery. The reed switches are biased, as by apermanent magnet, to a normally open position and so as to be operableto the closed position by a preselected pole of the bar magnet. Theswitches are positioned in the motor adjacent the ends of the bar magnetso as to be closable in a desired sequence as the bar magnet and motoroutput shaft rotate, thereby to commutate the conductor coils.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an exploded view of a priorart direct current motor and the commutator incorporated therein.

FIG. 2 is an exploded view of a motor constructed in accordance with thepresent invention and incorporating an improved commutation means.

FIG. 3 is a cross sectional, schematic diagram of magnetic reed switchesand the means for biasing them which may be incorporated in the improvedcommutation means shown in FIG. 2.

FIG. 4 is a schematic diagram of the direct current motor of FIG. 2showing the electrical connection of the commutation means in the motorand to a source of direct current.

FIG. 5 is a schematic diagram showing a modification of the directcurrent motor of the present invention.

FIG. 6 is an exploded view showing another modification of the directcurrent motor of the present invention in which the commutation meanshas been altered.

DESCRIPTION OF THE PREFERRED EMBODIMENT Direct current motor 10 includesan output shaft 12 which is rotated by the torque producingcurrent-magnetic field relationship established in motor 10 whenenergized from battery 14. A rotor 16 consisting of a bi-polar barmagnet having a north pole 18 and a south pole 20, is mounted on shaft12 so that the axis of the poles is perpendicular to the axis ofrotation of shaft 12. The poles 18 and 20 move in a circular path asshaft 12 rotates and the axis of poles generates a plane perpendiculartoshaft 12.

The stator of motor 10 comprises three bobbin wound windings 22, 24 and26. Each of the windings is wound on a spool 28 of generally rectangularconstruction and having a rectangular opening 30 in the center. The wireforming the stator windings is wound around the spool in reel-likefashion and the two ends of the coil-forming wire are extracted forconnection purposes hereinafter described.

The three windings are arranged on the frame of the motor (not shown)inessentially a closed equilateral triangular configuration, with eachwinding occupying one side of the configuration. The plane of thetriangular configuration lies per- I pendicular to the axis of rotationof shaft 12 but is coplanar with the plane of rotation of the polar axisof rotor 16. When the motor is assembled, the poles of rotor 16 areperiodically inserted in rectangular openings 30 of spools 28 as rotor16 rotates.

Stator windings 22, 24, and 26 are electrically connected in thefollowing manner. One end of each of the windings is connected to acommon junction 32. The other end of each of the windings is connectedto a commutation means to selectively provide electrical energization tothe windings in accordance in a predetermined switching sequence.

FIG. 1 shows a prior art commutation means used with direct currentmotor 10. The commutation means consists of a drum 34 mounted on shaft12 so that the axis of the drum is coaxial with the axis of rotation ofshaft 12. A pattern of electrically conductive and non conductive areasis placed on drum 34 to control the energization of windings 22, 24 and26 as rotor 16 rotates. A positive bus 36 lies along one edge of thesurface of drum 34 while a negative bus 38 lies along the other edge ofthe surface. Brush 40, connected to the positive terminal of battery 14,contacts positive bus 36 while brush 42, connected to the negativeterminal of battery 14, contacts negative bus 38. Brushes 40 and 42remain in contact with buses 36 and 38 for all rotary positions ofcommutator drum 34 and rotor 16.

A rectangular positive commutator segment 44 extends from positive bus36 for a portion of the length of the latter. A similarly shapednegative commutator segment (not shown) extends from negative bus 38 fora portion of the length of the negative bus. The commutator segments areseparated by a non conductive insulating area 46 which lies between thesegments and the buses.

The commutator brushes, connected to one end of each of windings 22, 24,and 26, are positioned so as to contact the positive and negativecommutator segments as commutator drum 34 rotates. Specifically,commutator brush 48 is connected to one end of winding 22, commutatorbrush 50 is connected to one end of winding 24 and commutator brush 52is connected to one end of winding 26. Commutator brushes 48, 50 and 52serve to selectively energize stator windings 22, 24 and 26 ascommutator drum 34 rotates.

In operation, with rotor 16 positioned as shown in FIG. 1, i.e., withnorth pole 18 inserted in opening 30 of winding 26, commutator drum 34is positioned so that brush 50 is in contact with positive commutatorsegment 44 to connect one end of winding 24 to the positive terminalbattery 14. Brush 48 is in contact with the negative segment ofcommutator drum 34 to connect winding 22 to the negative temiinal ofbattery 14. Winding 26 is deenergized. The electrical circuit iscompleted by common junction 32 so that conventional current flows fromthe positive terminal of battery 14 through winding 24, common junction32, and winding 22 to the negative terminal of battery 14. The currentcarrying conductors of windings 24 and 22 exert a torque on south pole20 of rotor 16 causing the rotor to rotate. The direction of rotation ofrotor 16 depends on the winding direction of the windings and may beassumed to be in the counter clockwise direction as shown in FIG. 1 bythe arrows.

As rotor 16 rotates, commutator drum 34 is also rotated to effect aselective connection of windings 22, 24 and 26 to battery 14 in a mannerto continue the rotation of rotor 16. For example, when rotor 16 hasrotated 60 degrees counter clockwise, commutator drum 34 has shifted toa position in which brush 48 has been moved off of the negative segmentto deenergize winding 22. Brush 52 has been moved onto the negativesegment to connect winding 26 to the negative ter minal of battery 14.Brush 50 remains in contact with positive commutator segment 44.Conventional current now flows from the positive terminal of battery 14through winding 24, common junction 32, and winding 26 back to thenegative terminal of battery 14. The current carrying conductors ofwindings 24 and 26 exert a torque on the north pole 18 of rotor 16 whichcontinues the rotation of rotor 16.

The above operation of motor continues with commutation occurring each60 of rotation of rotor 16 or 6 times per revolution of rotor 16. Amotor having the above described structure and mode of operation is madeand sold by the Hankscraft Company of Reedsburg, Wisconsin as a Series3000 display motor.

In the improved motor 10A of the present invention, the drum commutatoris replaced with magnetic reed switches operable by the magnetic fieldof bar magnet rotor 16. The mechanical and electro mechanical featuresof the magnetic reed switch commutation means are shown in FIGS. 2 and3. The electrical connection of the reed switches is shown schematicallyin FIG. 4.

Referring to FIG. 3, the details of a magnetic reed switch 60 suitablefor use in motor 10A are shown diagrammatically. Each reed switch 60includes an impervious vial or container 62 for containing the switchelements. Vial 62 is typically glass but may be other materials, such asmetal. Magnetic reed switches are typically single pole, double throwswitches in which the movable member or reed of the switch is normallybiased into one of the two throw positions. In FIG. 3, movable leaf reed64 is shiftable between reed 66 and reed 68 when a magnetic field isapplied to the switch. The movable reed may be constructed of soft ironor other magnetically responsive material for the purpose. Movable reed64 is normally biased against reed 66 and away from reed 68, as byspring 70. Reeds 64, 66 and 68 are connected to leads 72, 74 and 76 forinterposing the switch in the current carrying path to. be made orbroken. Each of the magnetic reed switches incorporated in directcurrent motor 10A of the present invention may be of the type describedand may, more specifically, be the magnetic reed switches manufacturedand sold by the Hamlin Mfg. Co. of Lake Mills, Wisconsin as C" Contact.type switches.

When incorporated in motor 10A, each of magnetic reed switches 60 hasassociated therewith a magnet which moves movable reed 64 out of thebiased position, in which it is in contact with reed 66, and intocontact with reed 68. For example, magnets 78 or 79 may be placed onvial 62 so as to move movable reed 64 into contact with reed 68 andretain it there. When movable reed 64 is in contact with reed 66,magnetic reed switch 60 is hereinafter termed closed" or in the closedposition or first position. When movable reed 64 is in contact with reed68, magnetic reed switch 60 is hereinafter termed open" or in the secondposition."

In order to provide the necessary switching or commutation function inmotor 10A, six magnetic reed switches 601 through 606 are utilized inthe commutation means, as shown in FIGS. 2 and 4. These magnetic reedswitches are grouped in pairs, a typical pair being shown in FIG. 3. Ineach pair of reed switches, there is one reed switch which is biased bya bar magnet 78 having a North pole-South pole orientation and one reedswitch which is biased by a magnet 79 having a South pole-North poleorientation. If necessary or desirable, the reed switches 60 may beseparated by a non magnetic divider, such as a piece of aluminum, andthe two reed switches, magnets, and the spacer bound into an integralunit as by a shrinkable tetrafluroethylene sleeve (not shown).

The pairs of reed switches are selectively operated by the bar magnet ofrotor 16 as the rotor rotates to efiect commutation of windings 22, 24and 26. For this purpose, it has been found convenient to mount thepairs of magnetic reed switches on the exterior of spools 28, as shownin FIG. 2. The switches are operated as the poles of rotor 16 areperiodically inserted in rectangular openings 30 of spools 28. Due tothe bias provided by bar magnets 78 and 79, the operation of themagnetic reed switches of each pair is one of mutual exclusivity. Thatis, north pole 18 of rotor 16 operates the one of the pair of magneticreed switches biased by the South pole-North pole bar magnet 79 byovercoming the magnetic bias of the bar magnet. The other of the pair ofmagnetic reed switches, that is, the one biased by the North pole-Southpole bar magnet 78, is retained in the biased position, as north pole 18or rotor 16 reinforces the bias supplied by bar magnet 78. When thesouth pole of rotor 16 is inserted in rectangular opening 30 of a givenspool 28, the operation of the magnetic reed switches is the opposite.

For each pair of magnetic reed switches, leads 72 are connected inparallel to an end of a stator winding, as shown in detail in FIG. 2 inconnection with magnetic reed switches 602 and 605. Lead 74 of one ofthe magnetic reed switches, for example, reed switch 605 is connected tothe positive terminal of battery 14, while the lead 74 of the othermagnetic reed switch, for example, magnetic reed switch 602 is connectedto the negative terminal of battery 14. Lead 76 of each of the magneticreed switches is not used.

The connection of the other magnetic reed switch pairs, reed switches601 and 604, and reed switches 603 and 606, to battery 14 is not shownin FIG. 2 for clarity, but is analogous to the connection of reedswitches 602 and 605. The connection of all magnetic reed switches is,however, shown in schematic form in FIG. 4. Paired reed switches 602 and605 connect winding 26 to the negative and positive terminals of battery14, respectively; paired reed switches 601 and 604 connect winding 24 tothe positive and negative terminals of battery 14, respectively; andpaired reed switches 606 and 603 connect winding 22 to the negative andpositive terminals of battery 14, respectively. Magnetic reed switches602, 604 and 606, which connect the negative temiinal of battery 14 towindings 26, 24, and 22 respectively, are all biased with the Southpole-North pole bar magnets 79 whereas magnetic reed switches 605, 601and 603, which connect the positive terminal of battery 14 to windings26, 24 and 22 respectively, are all biased with the North pole-Southpole bar magnets 78.

The operation of motor A is as follows. It may be assumed that rotor 16is rotating in the counter clockwise direction and is instantaneouslypositioned as shown in FIG. 4.

t In this position, north pole 18 of rotor 16 is inserted in rectangularopening 30 of coil 26. The magnetic field created by north pole 18causes magnetic reed switch 606 to close by overcoming the bias placedthereon by bar magnet 79. Closure of magnetic reed switch 606 connectsone end of winding 22 to the negative terminal of battery 14, as shownby the negative sign adjacent lead 74 of magnetic reed switch 606.

It may be assumed that the previous operation of motor 10A has leftmagnetic reed switch 601 closed, connecting one end of winding 24 to thepositive temiinal of battery 14, as shown by the positive sign adjacentlead 74 of magnetic reed switch 601. Conventional current thus flowsfrom the positive terminal of battery 14 through winding 24, commonjunction 32, winding 22, back to the negative terminal of battery 14.Winding 24 is deenergized. The current carrying conductors in the upperends of windings 22 and 24 exert a torque on the adjacent south pole 20of rotor 16 causing rotor 16 to rotate in the counter clockwisedirection.

When rotor 16 has rotated 60 counter clockwise, south pole 20 of rotor16 is inserted in rectangular opening 30 of winding 22. The south pole20 continues to maintain magnetic reed switch 601 closed, by overcomingthe bias placed on the magnetic reed switch by bar magnet 78. Thismaintains the connection of the positive terminal of battery 14 towinding 24. The 60 rotation of north pole 18 of rotor 20 opens magneticreed switch 606 deenergizing winding 22. The 60 rotation of north pole18 of rotor 20 also closes magnetic reed switch 602 which, similar tomagnetic reed switch 606, is biased by bar magnet 78. Lead 74 ofmagnetic reed switch 602 is also connected to the negative terminal ofbattery 14 so that closure of magnetic reed switch 602 causes winding 26to be connected to the negative terminal of battery 14. Conventionalcurrent now flows from the positive terminal of battery 14 throughwinding 24, common junction 32, and winding 26 back to the negativeterminal of battery 14. The current carrying conductors of windings 24and 26 exert a torque on the north pole 18 of rotor 16 which continuesthe rotation of rotor 16.

The above described operation of motor 10A continues with commutationoccurring each 60 of rotation of rotor 16 or six times per revolution ofrotor 16. The switching sequence is shown in tabular form below.

Rotor Position Condition of Stator Winding (defined by pole (switches inclosed position) insertion in specified winding) Winding 22 Winding 24Winding 26 N pole winding 26 606 601 deen. S pole winding 22 deen. 601602 N pole winding 24 603 deen. 602 S pole winding 26 603 604 deen. Npole winding 22 deen. 604 605 S pole winding 24 606 deen. 605

The direction of motor rotation may be reversed by reversing theconnection of battery 14 to motor 10A.

In some applications it may be desirable to pass more current throughwindings 22, 24 and 26 than can be safely handled by magnetic reedswitches of the general type shown in detail in FIG. 3, or to reduce thecurrent through the magnetic reed switches. In such cases, the magneticreed switch pairs may be utilized to drive the pair of complementarytransistors, as shown in FIG. 5. FIG. 5 shows magnetic reed switches 601and 604 connected in parallel between battery 14 and the base terminalsof a complementary pair of transistors 6011 and 6041. Transistor 6011may be of the NPN type while transistor 6041 may be of the PNP type. Thecollector of transistor 601 1 is connected to the positive terminal ofbattery 14. The emitter of transistor 6011 is connected in series withthe emitter of transistor 6041, the collector of which is connected tothe negative terminal of battery 14. The common junction of the emittersof transistors 6011 and 6041 is connected to winding 22 by conductor 90.

In operation, magnetic reed switches 601 and 604 are operated by rotor16 in the manner described above. The current from battery 14, appliedthrough one or the other of magnetic reed switches 601 and 604, rendersone or the other of transistors 6011 and 6041 conductive to providecurrent from battery 14 through conductor to winding 22 thus providingamplification to the operation of the magnetic reed switches. Forexample, the closure of magnetic reed switch 601 renders transistor 6011conductive to connect the positive terminal of battery 14 to winding 22,via conductor 90. Similarly, the closure of magnetic reed switch 604renders transistor 6041 conductive to connect the negative terminal ofbattery 14 to winding 22. Transistors 6011 and 6041 thus provideamplification to the operation of magnetic reed switches 601 and 604.

Another modification of the motor of the present invention is shown inFIG. 6 as motor 108. A small auxiliary bar magnet rotor 116 is mountedon an extension of rotor shaft 12 in the same angular position as mainbar magnet rotor 16. The pairs of magnetic reed switches 60 and barmagnets 78 and 79 are mounted on the frame of motor 108 (not shown) soas to be operable by auxiliary rotor 116. The magnetic reed switches areconnected to windings 22, 23, and 26 in the same manner as describedabove and the operation of motor 103 is analogous to that of motor 10A.Since the torque arm of rotor 116 is smaller than the torque arm ofrotor 16, motor 108 is usable in cases in which the effect of themagnetic interaction of the motor rotor and the bar magnets 78 and 79associated with the magnetic reed switches must be kept to a minimum.

Other changes in the form and details may be made to the motor of thepresent invention without departing from the spirit and scope thereof.

Various modes of carrying out the invention are contemplated as beingwithin the scope of the following claims particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention.

I claim:

1. An electric motor suitable for connection between the positive andnegative terminals of a direct current source comprising:

a rotatable output shaft;

a rotor mounted on said output shaft having a pair of mag- .neticallyopposite poles rotatable, with said shaft, in a circular path;

a plurality of energizable'windings of current carrying conductorsselectively connectable to the direct current source and positioned withrespect to said rotor to provide a rotation-producingtorque on saidrotor when energized; and

commutation means interposed between said windings and the directcurrent source for sequentially connecting said windings to the directcurrent source responsive to the rotation of said rotor, saidcommutation means being spacedly located along the circular path of saidrotor and comprising a plurality of switch groups equal in number to thenumber of motor windings, each of said switch groups comprising a pairof single pole, double throw, magnetic reed switches having bias meansurging said switches into a normally closed first position and having anopen second position, one switch of each pair being interposed betweenone of said motor windings and the positive temiinal of the directcurrent source for energizing the former from the latter when in thefirst position, the other switch of each pair being interposed betweenthe one of said windings and the negative terminal of the direct currentsource for energizing the former from the latter when in the firstposition, the switches of each pair having oppositely poled magneticbias means associated therewith for overcoming the first position biasmeans of said switches to place said switches in the second position andfor allowing opposite polarity magnetic poles of said rotor to retum theswitches to the normally closed first position when in proximity to saidswitches, thereby selectively energizing said windings from said directcurrent source.

2. The electric motor according to claim 1 wherein the poles of saidrotor are movable in a plane perpendicular to the axis of rotation ofthe output shaft, wherein said windings are bobbin wound and arranged onthe plane of rotation of the rotor poles so that the poles areperiodically inserted in the windings as said rotor rotates, said switchgroups being mounted on said windings for being operated by said rotorwhen the rotor poles are periodically inserted in the windings.

3. An electric motor according to claim 1 including a settliconductorcurrent control means having power circuits interposed between thedirect current source and the windings and control circuits connected tosaid switch groups for operating said power circuits for sequentiallyconnecting said windings to the direct current source.

iliary magnetic member mounted on the output shah and 4. An electricmotor according to claim 3 including a semiconductor current controlmeans, said semi-conductor current control means comprising pairs ofcomplementary transistors, said transistors having power circuitsconnected between said windings and the direct current source, each ofsaid pairs of transistors having control circuits connected in parallelto a switch group for complementary operation of the transistor pairwhen the magnetic reed switches are in the first position.

5. An electric motor according to claim 1 including an auxrotatabletherewith in synchronism with said rotor, said auxiliary magnetic memberhaving a pair of magnetically opposite poles rotatable with said shaftin a circular path; said-switch groups being spacedly located along thecircular path of the auxiliary magnetic member for sequentiallyconnecting selected windings to the direct current source forenergization as the motor shaft rotates.

UNITED STATES PATENT OFFICE (3ER'PIjFlCA'lTE (1.) b CORRECTION Patent3.678.359 Dated Julv 18. 1972 In DONOVAN F. PETERSON It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Col; 5, lines 50-60 Rewrite the table as follows:

Rotor Position Condition of Stator Winding (defined by pole switches inclosed position) insertion in specified winding) Winding 22 Winding 24Winding 26 N pole winding 26 606 j 601 deen.

S pole winding 22 deen. 601 602 N pole winding 24 603 deen. 602

S pole winding 26 603 g 604 deen.

N pole winding 22 deen. 604 r 605 S pole winding 24 606 deen. 605

Signed andsealed this 23rd day ofJanuary 1,973.,

(SEAL) Attest: v

EDWARD M.PLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM PO-105O (10-69) uscoMM-De sows-ps9 U.S. GOVERNMENTPRINTING OFFICE: I969 O366-334 UNITED STATES PATENT OFFICE CERTIFICATE UB? CU Efi'HiNY Patent No. 3 678 359 Dated Julv 18. 1972 Inventor(s)DONOVAN F. PETERSON It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

001; 5, lines 50-60 Rewrite the table as follows:

Rotor Position Condition of Stator Winding (defined by pole (switches inclosed position) insertion in t v specified winding) Winding 22 Winding24 Winding 26 N 616 winding 26 606 f 601 deen.

S pole winding 22 deen. 601 602 Q N p016 winding 24 603 deen. 602

S pole winding 26 603 604 deen.

N 6616 winding 22 deen. 604 606 S pole winding 24 606 deen. 605

Signed and sealed this 23rd day of January 1973.,

(SEAL) Attest:

EDWARD 1 '1.1 LETCI-IER,JR. ROBERT GOTTSCHALK Attesting OfficerCommissioner of Patents FORM PO-OSO (10-69).

USCOMM-DC 60376-F'69 v u.s. GOVERNMENT PRINTING OFFICE I569 o3ss-324

1. An electric motor suitable for connection between the positive andnegative terminals of a direct current source comprising: a rotatableoutput shaft; a rotor mounted on said output shaft having a pair ofmagnetiCally opposite poles rotatable, with said shaft, in a circularpath; a plurality of energizable windings of current carrying conductorsselectively connectable to the direct current source and positioned withrespect to said rotor to provide a rotation-producing torque on saidrotor when energized; and commutation means interposed between saidwindings and the direct current source for sequentially connecting saidwindings to the direct current source responsive to the rotation of saidrotor, said commutation means being spacedly located along the circularpath of said rotor and comprising a plurality of switch groups equal innumber to the number of motor windings, each of said switch groupscomprising a pair of single pole, double throw, magnetic reed switcheshaving bias means urging said switches into a normally closed firstposition and having an open second position, one switch of each pairbeing interposed between one of said motor windings and the positiveterminal of the direct current source for energizing the former from thelatter when in the first position, the other switch of each pair beinginterposed between the one of said windings and the negative terminal ofthe direct current source for energizing the former from the latter whenin the first position, the switches of each pair having oppositely poledmagnetic bias means associated therewith for overcoming the firstposition bias means of said switches to place said switches in thesecond position and for allowing opposite polarity magnetic poles ofsaid rotor to return the switches to the normally closed first positionwhen in proximity to said switches, thereby selectively energizing saidwindings from said direct current source.
 2. The electric motoraccording to claim 1 wherein the poles of said rotor are movable in aplane perpendicular to the axis of rotation of the output shaft, whereinsaid windings are bobbin wound and arranged on the plane of rotation ofthe rotor poles so that the poles are periodically inserted in thewindings as said rotor rotates, said switch groups being mounted on saidwindings for being operated by said rotor when the rotor poles areperiodically inserted in the windings.
 3. An electric motor according toclaim 1 including a semi-conductor current control means having powercircuits interposed between the direct current source and the windingsand control circuits connected to said switch groups for operating saidpower circuits for sequentially connecting said windings to the directcurrent source.
 4. An electric motor according to claim 3 including asemi-conductor current control means, said semi-conductor currentcontrol means comprising pairs of complementary transistors, saidtransistors having power circuits connected between said windings andthe direct current source, each of said pairs of transistors havingcontrol circuits connected in parallel to a switch group forcomplementary operation of the transistor pair when the magnetic reedswitches are in the first position.
 5. An electric motor according toclaim 1 including an auxiliary magnetic member mounted on the outputshaft and rotatable therewith in synchronism with said rotor, saidauxiliary magnetic member having a pair of magnetically opposite polesrotatable with said shaft in a circular path; said switch groups beingspacedly located along the circular path of the auxiliary magneticmember for sequentially connecting selected windings to the directcurrent source for energization as the motor shaft rotates.